[Radioresistant elements in adenocarcinoma of the uterus]

Radioresistant elements in adenocarcinoma of uterine cancer were studied using SKG-3a and HEC-59 cell lines as spheroids and monolayer culture. Dose-survival curves for monolayer cultured SKG-3a and HEC-59 cells were almost similar at acute exposure. On the other hand, as spheroids grown to 300 microns in diameter, dose-survival curves for SKG-3a cells were biphasic and those for HEC-59 were monophasic. The increased shoulder in survival curves proved the contract effect of both cells. Conventionally fractionated irradiation promoted shrinkage and disintegration of spheroids as the dose was increased. All SKG-3a spheroids were destroyed over 60 Gy, but some of HEC 59 spheroids survived over 68 Gy at the total dose. The total dose at disintegration-50% was 40 Gy in SKG-3a and 48 Gy in HEC-59 spheroids. In a comparison of single with 5-fractionated irradiation, fractionation induced an increase in radioresistance of adenocarcinoma cells. The maximum recovery-dose of HEC-59 cell as spheroids was 0.4 Gy and that of SKG-3a was 0.28 Gy. The magnitude of PLD-repair in HEC-59 cells was greater than that in SKG-3a. In conclusion, the PLD-repair and contact effect could be more important factors than the hypoxic element in the acquisition of radioresistance in adenocarcinoma cells as a solid tumor under fractionated irradiation.